<!DOCTYPE html>

<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .loop {
            border: 16px solid red;
            width: 200px;
            height: 200px;
            border-top: 16px solid green;
            border-radius: 50%;
            animation: move 2s linear infinite;
        }

        @keyframes move {
            0% {
                transform: rotate(0deg);
            }

            100% {
                transform: rotate(360deg);
            }
        }
    </style>
</head>

<body>
    <div class="loop"></div>
</body>

</html>